Green’s Dictionary of Slang

(mainly Aus./N.Z.) an adversary worthy of consideration.

1843		L.H. Medina Nick of the Woods I iii: Who’s for a fight? [...] Ain’t I the old snag to shake off a saddle – can go down the Old Salt on my back and swim up the Ohio! Hurrah for a fight!
1885		Ames Advance (KS) 16 Oct. 6/4: ‘You fellers are tryin’ to play me for a sucker, but by the eternal, you’ve struck the wrong snag’.
1902		Bulletin (Sydney) 6 Sept. 15/4: Religion did not mean being knock-kneed and anæmic. Any man who thought that and tackled Sandow would find that he had run up against a ‘snag.’.
c.1905		J. Furphy Rigby’s Romance (1921) Ch. xiv: 🌐 Grand thing to be a (adj.) snag like him. Sort o’ gift.
1911		E.S. Sorenson ‘Bush Cooks’ in Life in the Aus. Backblocks 91: Concerning fighting cooks the tales are legion. I remember one snag in a north-western (New South Wales) shed, who cooked abominably, but rendered his position tenable by punching the ringer, spreading out the shed pug, and knocking pieces off the wool-presser.
1919		Gippsland Times (Vic.) 11 Sept. n.p.: Mr Stephenson said the Acting Mayor was a ‘tough snag’ to run up against.
1923		Sun. Times (Perth) 11 Feb. 1s/4: You big rotten mongrel! [...] I’ll show you what a snag you’ve struck!
1929		J. Devanny Riven 115: That chap is a bit of a snag.
1952		G. Meek ‘The Ballad of the Rouseabout’ Station Days in Maoriland 94: Like workmen, down we flopped. / And rolled our fags, and talked of snags / Of bosses, we had struck – The stingy sort, and real good sport.
1975		Bulletin (Sydney) 26 Apr. 46: But the fucking mug was a nice snag and nearly got away with Punchy.
2003		McGill Reed Dict. of N.Z. Sl. 193: snag [...] 2 Person or thing giving you a tough time, from ‘snag’, an obstacle.